Rejection of Sinusoidal Disturbance of Unknown Frequency in Linear Systems with Unknown Input Delay

We introduce a method with the aim of rejecting a sinusoidal disturbance with unknown frequency, while acting on unstable LTI plants with unknown delay in input. In this method, we use modified second order generalized integrator frequency locked-loop (Modified SOGI-FLL) for frequency estimation and building two orthogonal sinusoidal signals, which by applying algebraic operations on them, the disturbance rejection law is built. Since the plant is unstable with an unknown input delay, we use the predictor feedback and its delay update laws for stabilizing and delay estimation. Simulation results show the well performance of the method.